1 | <script>
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2 | import { memoize } from 'lodash';
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3 |
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4 | const getObserver = memoize(
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5 | (options) =>
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6 | new IntersectionObserver((entries) => {
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7 | entries.forEach((entry) => {
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8 | entry.target.$_gl_intersectionHandler(entry);
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9 | });
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10 | }, options || {})
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11 | );
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12 |
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13 | export default {
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14 | name: 'GlIntersectionObserver',
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15 | props: {
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16 | /**
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17 | * Extra options to pass directly to the intersection observer API.
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18 | */
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19 | options: {
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20 | type: Object,
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21 | required: false,
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22 | default: null,
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23 | },
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24 | },
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25 | mounted() {
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26 | const observer = getObserver(this.options);
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27 |
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28 | this.$el.$_gl_intersectionHandler = (entry) => {
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29 | /**
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30 | * Emitted when the element's visibility changes
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31 | */
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32 | this.$emit('update', entry);
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33 |
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34 | if (entry.isIntersecting) {
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35 | /**
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36 | * Emitted when the element appears on the page
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37 | */
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38 | this.$emit('appear');
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39 | } else {
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40 | /**
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41 | * Emitted when the element disappears from the page
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42 | */
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43 | this.$emit('disappear');
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44 | }
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45 | };
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46 | this.$el.$_gl_intersectionObserver = observer;
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47 |
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48 | observer.observe(this.$el);
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49 | },
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50 | destroyed() {
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51 | this.$el.$_gl_intersectionObserver.unobserve(this.$el);
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52 | delete this.$el.$_gl_intersectionHandler;
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53 | delete this.$el.$_gl_intersectionObserver;
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54 | },
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55 |
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56 | getObserver,
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57 | };
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58 | </script>
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59 |
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60 | <template>
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61 | <div>
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62 | |
63 |
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64 |
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65 | <slot></slot>
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66 | </div>
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67 | </template>
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